Definition

The middle ear, located behind the eardrum, contains three auditory ossicles that transmit sound vibrations from the outer to the inner ear. The inner ear then converts these vibrations into electrical signals that the brain interprets as sound.

Otosclerosis is a rare condition that causes hearing loss. The term "otosclerosis" comes from "oto" (ear) and "sclerosis" (abnormal hardening of body tissue). In otosclerosis, the stapes bone becomes stiff and fuses with surrounding bones, preventing it from vibrating and thus hindering sound transmission to the inner ear.

Causes

Otosclerosis occurs when the base of one of the bones in the middle ear, the stapes, becomes stiff, making it unable to vibrate to transmit sound. It could be caused by abnormal tissue growth around the stapes bone or abnormalities in the stapes bone remodeling process, which involves continuously replacing old bone tissue with new bone tissue. 

The exact mechanism that causes this condition has not been known in otosclerosis. Scientists have suspected that otosclerosis is associated with a history of measles infection, fractures around the inner ear, or immune disorders.

Otosclerosis often occurs in families and is believed to be associated with an imbalance in cytokines, which are proteins in the immune system. Researchers suggest maintaining a balance of these cytokine proteins is crucial for healthy bone remodeling. An imbalance in these proteins can disrupt bone remodeling, leading to conditions like otosclerosis.

Risk factor

Otosclerosis occurs in more than 3 million people in the United States. Experts do not yet know the exact cause of otosclerosis. However, the following factors have been proven to increase the risk of otosclerosis, namely :

Age

Otosclerosis typically begins between the ages of 10 and 45, with most cases occurring in the 20s. The most severe symptoms usually appear in the 30s.

Genetic Factors

This disease is often found to have genetic predilections. About 50% of individuals with otosclerosis have a family history. While genetic predisposition increases the risk, it does not guarantee the development of otosclerosis.

Gender

Both men and women can develop otosclerosis, but women are at higher risk. The reason for this gender difference is unclear.

Pregnancy

Pregnancy can accelerate the progression of hearing loss in women with otosclerosis compared to non-pregnant women.

Race and ethnicity

Otosclerosis is more common in Caucasians, affecting about 10% of this population. Meanwhile, this disease is rare in African Americans.

Medical history

Certain medical conditions, such as a history of measles infection, fractures around the inner ear, and immune disorders, can increase the risk of developing otosclerosis.

Symptoms

The primary symptom of otosclerosis is gradually worsening hearing loss. Initially, individuals may struggle to hear low-pitched sounds or whispers. Over time, the symptoms typically worsen. About 70% of people with otosclerosis experience hearing loss in both ears, while 10% to 15% have hearing loss in just one ear.

Other potential symptoms include:

• Dizziness
• Vertigo
• Balance problems
• Tinnitus, which involves ringing or buzzing sounds in the ears and usually disappears after surgery

Otosclerosis is often associated with osteogenesis imperfecta (a congenital disorder where bones break easily), with symptoms such as deafness, spontaneous bone fractures, and blue sclera (white eye membrane).

Diagnosis

If you experience hearing loss, consult an otolaryngologist. The doctor will examine your ears and hearing function and inquire about the symptoms you and your family members may experience and your medical history. An audiometry test may be performed to assess hearing loss.

In some cases, the doctor may recommend a CT scan to support the diagnosis by providing detailed images of the inside of the ear and its surroundings. The slices of images will be taken from various angles and combined to create a more detailed image.

Management

Otosclerosis typically worsens over time, and your doctor will recommend appropriate therapies or steps based on your condition.

Observation
For mild otosclerosis, doctors usually monitor symptoms and conduct regular hearing check-ups without taking special action yet. They may also suggest using hearing aids.

Auxiliary Device
Hearing aids cannot cure otosclerosis but can improve hearing impairment caused by the condition.

Surgical Procedures
For severe or worsening hearing loss, your doctor may recommend a surgical procedure called a stapedectomy. In this procedure, the surgeon places a device in the middle ear to help mobilize the stiff stapes bone, allow sound waves to reach the inner ear, and improve hearing.

Stapedectomy can be effective for many patients and is considered safe, with a success rate of around 94.2%. However, as with any procedure, there are risks, and in rare cases, surgery could worsen hearing loss. 

If both ears are affected, the surgeon will typically operate on one ear first and wait for at least six months before operating on the other.

Complications

Complications of otosclerosis include hearing loss, while postoperative complications are rare. These complications can include:

• Complete deafness
• Necrosis (tissue death) of the incus ossicle
• Perforation of the eardrum
• Facial nerve injury
• Taste disorders
• Detachment of the stapes bone from its attachment point
• Vertigo 

Surgical procedure failures are usually due to incorrect positioning or inappropriate instrument sizing in the inner ear.

Prevention

There is no definitive way to prevent otosclerosis. Early detection is crucial for providing appropriate treatment and preventing further hearing loss. 

Unlike other hearing disorders, otosclerosis lacks preventable risk factors. Some individuals may have genetic predilections inherited from their parents that may increase the risk of otosclerosis, making it difficult to prevent the condition.

After otosclerosis surgery, follow these steps to protect your inner ear from infection, pressure, and noise, reducing the risk of complications:

• Avoid exhaling breath forcefully or with pressure
• Steer clear of cold temperatures
• Minimize the risk of upper respiratory infections by avoiding contact with sick individuals
• Avoid conditions associated with changes in air pressure, such as during air travel or diving
• Stay away from loud noises
• Consult a doctor immediately if you experience ear pain, dizziness, or fever, as these could indicate an infection

When to see a doctor? 

Consult a doctor if you have risk factors for otosclerosis or experience:

• Hearing disorders
• Fever
• Pain in the ears
• Dizziness
• Other symptoms following surgery for otosclerosis

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